STM32F446RE: why ADC output has and offset by 300 mV for various analog input?

[d146]

Hi,

I'm working on STM nucleo board (STM32F446RE) currently.I'm using ADC Channel 0 and 1.I have found that the ADC output has and offset by 300 mV for various analog input. Please explain the cause.

/* code snippet to read ADC Channel 1 output*/

for( int i=0; i<SIZE; i++)

adc2[i] = TM_ADC_Read(ADC1, ADC_Channel_1);

[waclawek.jan]

How do you calculate the voltage from ADC readout? What is the input source, is it low impedance enough/is the sampling time long enough?

JW

[Ozone]

ADCs are inputs.

Most probably, this offset exist already at the inputs, from your hardware.

Or, as Jan suggested, your sampling time is much too short.